What Causes Hot Flashes?

Help, It’s Like a Furnace In Here!

As soon as women experience their first menopause symptoms with the dreaded “power surges”, they are wondering what causes hot flashes?

We will give you a stripped down scientific version about the causes of hot flashes. (BTW: Night sweats have the same underlying mechanisms.) As you can see, it is a very complex issue which explaines why it is so difficult to find the perfect treatment.

What are Hot Flashes?

What causes hot flashes can be answered by looking at the effects of the changing hormone levels on the brain. The changes in estrogen and progesterone affect the brain’s regulation of the core body temperature.

Following is a greatly simplified version of what causes hot flashes. In reality this is more complicated and there are still a lot of unanswered questions.

What happens when you have hot flashes:


The normal core body temperature fluctuates roughly between 96.8 and 99.5 degrees Fahrenheit (36 -37.5 degrees Celsius). Your core body temperature fluctuates slightly throughout the day and is lowest in the later phase of the sleep cycle.

Humans have a very small temperature range (usually about 1.8 degrees Fahrenheit) which is perceived as “normal”: neither too hot nor too cold.

This is called the Thermoneutral Zone or the temperature range where you neither sweat nor shiver.

Within this neutral temperature range the brain does not try to raise or lower the core body temperature.

Women with hot flashes have NO (or a very small) thermoneutral zone, as recent research has indicated.

This means that every slight increase in the core body temperature triggers a “heat dissipation” response by the brain. – This response is what causes hot flashes.

The breakdown of this thermoneutral zone is caused by an overactive central nervous system. Affected is the “call for action” or sympathetic system. It triggers increases in blood pressure, a faster heart beat and sweating.

When the body perceives that the body temperature is too low, the opposite happens and you shiver to bring it back to a normal range


These changes and false messages to the brain are caused by ….

… estrogen!

(You were probably wondering when we were getting around to the hormone connection!)

Estrogen influences the neurotransmitters that are the messengers between the body functions and the regulating systems in the brain.

Different hotflash treatments influence different parts of the chain reactions:

  • Some treatments widen the thermoneutral zone
  • Other treatments restore the proper function of the neurotransmitters.

The effect of estrogen (and other hormones as well) on these neurotransmitters is still not fully understood. Researchers know that many neurotransmitters are affected by estrogen.

One example of these neurotransmitters is serotonin, which plays an important role in mood regulation. Serotonin drugs, which were developed for the treatment of depression, are sometimes prescribed for menopause symptoms.

This also explains, why smoking, being overweight and having a lot of stress act as symptom triggers. All these factors influence different neurotransmitters.

A Little Bit of Historic Background

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The research into what causes hot flashes is relatively new. In the 19th century doctors (remember they were mostly men), thought that hot flashes where all in our heads and part of a mysterious female disorder called “hysteria”.

With the advances of modern science came the theory that the drop in estrogen was the culprit, hence the prescription of estrogen hormones as a treatment.

However, not every woman with low estrogen levels has hot flashes and women with hot flashes have different estrogen levels. So it is clear that the causes of hot flashes are more complicated than just a drop in estrogen.

But at least now we do know that estrogen influences numerous pathways of the central nervous system. Fluctuating and changing estrogen levels during the menopause transition can affect several aspects of your temperature control system.

Ready to find out about how to treat your symptoms?

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